Dear sir
my project is to measure heart beat using LM324,IR LED,phototransistor
and microcontroller 89c52.In my project I am facing a problem that i unable to count the pulse by 89c52.I am using 89c52 in counter mode and giving the input through p3.4 the input is the output of the LM324 by placing finger between IR LED and PHOTOTRANSITOR and this output changes their state continuosly high-low-high-low......according to that a LED connected at this position is ON-OFF-ON-OFF.....continuosly but this event is not counted by 89c52 properly for 15 second (actually i want to count for 15 second afterthat multiply the count by 4 to get the total count in one minute) but 89c52 is not counting properly please help me in this regard